Urinary incontinence, bladder overactivity, sexual dysfunction, and other pelvic floor disorders are common problems affecting people of all ages, gender and race.
Overactive bladder (OAB) is a condition that affects millions of citizens worldwide. OAB is a urological condition defined by a set of symptoms: urgency, with or without urge incontinence, usually with frequency and nocturia. Frequency is usually defined as urinating more than 8 times a day. Symptoms of OAB can include urinary frequency, urinary urgency, and urinary urge incontinence due to a sudden and unstoppable need to urinate, nocturia or enuresis resulting from overactivity of the detrusor muscle. The major symptom of OAB is a “gotta go” feeling, —the sudden, strong urge to urinate that the patient can't control. Sometimes people with OAB also have “urgency incontinence”. This means that urine leaks after they feel the sudden urge to go. Carrying out the activities of daily life and engaging in social and occupational activities can be profoundly affected by lack of bladder control and incontinence. OAB may cause significant social, psychological, occupational, domestic, physical, and sexual problems, with social and professional isolation.
Urinary incontinence is defined as an involuntary loss of urine. Women experience this condition twice as often as men. Pregnancy and childbirth, menopause, and the structure of the female urinary tract account for this difference. Both women and men can become incontinent from neurologic injury, birth defects, stroke, multiple sclerosis, and physical problems associated with aging. The US Department of Health and Human Services estimates that approximately 13 million Americans suffer from urinary incontinence. Urinary incontinence is an underdiagnosed and underreported problem that increases with age, affecting 50-84% of the elderly in long-term care facilities. Urinary incontinence is at any age more than 2 times more common in females than in males. 10% to 30% of American women/girls aged 15-64 years are thought to suffer from it, compared to between 1.5% and 5% of men. Over half of all nursing home residents are thought to be affected by urinary incontinence. It is estimated that 20% of all women over the age of 40 are affected by urinary incontinence.
Sexual dissatisfaction and/or trouble with penis/clitoris erection affects both women and men. In men, erectile dysfunction is the inability to achieve and sustain an erection suitable for sexual intercourse. Occasional erectile dysfunction are not uncommon. Many men experience it during times of stress. It can also be a sign of emotional or relationship difficulties that may need to be addressed by a professional. Up to 30 million American men are affected by erectile dysfunction. Risk for such sexual dysfunction in men increases with age. Women's sexual health, like men's, is important to overall emotional and physical well-being. Many people think that sexual activity is motivated by physical desire, such as the desire of the body to want sex, which leads to sexual arousal and then orgasm. Although this may be true for men, research suggests that women's sexual motivations and responses may be more complex. For many women, particularly those who are older than 40 or who have gone through menopause, physical desire isn't the primary motivation for sex. What it means to be sexually satisfied may differ for men and women, and even among women. Some women say the pleasure of sexual arousal is sufficient, while others want to experience orgasm.
The three most common sexual dysfunctions in males are decreased libido, erectile dysfunction (ED) and ejaculatory dysfunction. ED is a common problem in primary care and currently affects more than 150 million men worldwide, with a projected prevalence increase to 322 million men by the year 2025. ED has a significant impact on patient's quality of life, self-confidence and interpersonal relations. The safety and efficacy of phosphodiesterase 5 (PDE5) inhibitors has been well documented. First-line therapy for treatment of ED is medication with a PDE5 inhibitor. A contraindication for the use of PDE5 inhibitors is the intake of nitrates, and patients with severe cardiovascular comorbidities should not use a PDE5 inhibitor. Up to 50% of patients suffering from ED present a suboptimal answer to the PDE5 inhibitors. During recent years, downsizing of catheter material has facilitated endovascular revascularization of small-caliber erection-related arteries.
In a study known as the ZEN study (Rogers J H, Goldstein I, Kandzari D E, Kohler T S, Stinis C T, Wagner P J, et al. Zotarolimus-eluting peripheral stents for the treatment of erectile dysfunction in subjects with suboptimal response to phosphod-iesterase-5 inhibitors, J Am Coll Cardiol. 2012; 60(25):2618-27), procedural success was 100% with no major adverse events during follow-up. About 60% of patients undergoing stent placement showed functional improvement subsequent to endovascular revascularization. However, the restenosis rate was reported to be as high as 34% in these small-caliber arteries after 6 months of follow-up.
Electrical stimulation of pelvic nerves in the pelvic floor may provide an effective therapy for a variety of disorders. Electrical stimulation has emerged as an alternative and attractive treatment for refractory cases of bladder overactivity, urinary incontinence and also bladder retention (incapacity of bladder voiding). In urinary incontinence and bladder overactivity, because the stimulation of the pudendal nerve induces a relaxation of the bladder muscle, and a contraction/closure of the urethral sphincter, it aids the patient in reducing unwanted urinary voiding, and pain due to overactive bladder. Also the stimulation may be effective in restoring sexual function or alleviating pelvic floor or genital pain.
Stimulation leads are ordinarily implanted surgically or percutaneously.
Sacral nerve stimulation enables stimulation of pudendal fibers—the key player of the functions of the pelvic organs including the genital organs—contained in the sacral nerve root, and also activates other fibers that are present in the sacral nerve root. This in turn produces some patient discomfort such as feeling of electricity in the leg. Also because the fibers of the pudendal nerve are dispatched between the sacral nerve roots S2, S3 and S4, only stimulation of all three roots together can reach all pudendal fibers together. However in the actual form of sacral nerve stimulation, a technique called Interstim—Medtronic, one lead can only stimulate one nerve.
Pudendal nerve stimulation includes stimulation of active sensoric and motoric fibers designed for the urinary bladder, the rectum, the sexual organs and both the anal and urethral sphincters. Neuromodulation of the pudendal nerve enables optimal control of bladder overactivity, fecal and urinary incontinence—especially in combination. The “pudendal LION Procedure” permits the implantation of a lead at the origin of the nerve at the level of the less sciatic notch via a laparoscopic approach. This approach also permits a selective exposure of the dorsal nerve of the clitoris/penis but the dissection is laborious, requiring transection of the sacrospinal ligament and an absolute expertise in laparoscopic advanced neuropelveological surgery. All further techniques of implantation of a lead to the pudendal nerve are based on the percutaneous implantation below the pelvic floor. So the transobturator procedure (Transobturator lead implantation for pelvic floor stimulation—Siegel—US Patent 2007/0173900) permits implantation of a lead electrode by percutaneous implantation technique to the pudendal nerve or even to the dorsal nerve of the penis/clitoris (DNP) below the pelvic diaphragm, close to the ischium in proximity to the sciatic spine where the nerve emerges from the pudendal nerve (Abb 1-2). Because the lead cannot be fixed to any anatomical structures, such techniques of implantation below the pelvic floor always expose the patient to risk of electrode breakage, dislocation and migration.
Because part of the DNP lies superficially to the skin outside the pelvis, this nerve can be stimulated using surface electrodes attached to the overlying skin. This application is also limited due to intolerance to the required high stimulation amplitude. In patients with intact sensitivity, this leads to stimulation amplitudes that are less effective or too low to be effective, which subsequently results in incontinence. Surface electrodes have additional limitations such as difficulties in daily proper placement and hygiene.
Implanted electrodes are more suitable, but implanted electrodes in the penis or near the clitoris have to endure mechanical stress of penile erections and external pressure, with risk for cable/electrode breakage and dislocation.
A technique for percutaneous implantation of an electrode near the origin of the DNP close to the Alcock's canal have also been developed. Because such technique lacks direct vision to the nerve during implantation, X-ray screening and neuro-physiological monitoring of the nerve are usually mandatory. The technique is not easy and also exposes patients to electrode migration and failure since the lead is not fixed to any anatomical structure and patients are sitting on the lead.
Providing a controlled and sustained penile erection for a disabled patient also includes stimulation of the cavernous nerves (CN), which nerves contain major genital parasympathetic fibers (Eckhard, Untersuchung über die Erektion des Penis beim Hunde. Beiträge zur Anat. Und Physologie, vol iii, Giessen 1863). Stimulation of the CN produces a sustained reflex erection by increasing filling of the penis via dilatation of penile arteries, and at the same time preventing leakage via occlusion of penile veins. Pelvic sympathetic nerves are theoretically responsible for detumescence, but electrical stimulation of the sympathetic pathways to the penis also may produce erection (K-E Andersson, P Hedlund, P Alm2. Symptahetic pathways and adregernic innervation of the penis. Int. J. of Impotence Research 2000; 12, Suppl 1:5-12). The classical location for electrode placement is at the inferior hypogastric plexus close to the apex of the prostate. However, this technique requires surgical exposure of the pelvic plexus, the lateral bladder and rectal wall and the inferior hypogastric plexus and intraoperative neuronavigation for identifying the bundle of cavernous nerves.
None of the previous techniques permit an approach to the dorsal nerve of the penis/clitoris or to the cavernous nerves, or to the genital sympathetic nerves below the pubic arch (which is anatomically not feasible) where the nerve passes down to the sexual organs. Further, a percutaneous approach coming from lateral or dorsal to the location of the nerve below the pubic bone would expose the patient to high risk of damage to the deep dorsal vein and to the lateral venous plexus with, as a consequence, massive hemorrhaging and risk of death.
None of the above mentioned methods enable bilateral and concomitant stimulation of the genital nerves. Unilateral stimulation may induce a unilateral erection and deviation of the penis in men.